BTW, to gain some cm and be able to have the full cabin as well as making it easier to operate, the mount was installed outside the rear window, not into the cabin

then you have the one taken from the soon roof.
As for the comparison between 964 and 996, well, it's difficult to put the finger on it. They feel very similar and you couldn't doubt a split of a second they are deeply related. If offered a change I'd keep the 964. It's as comfortable but doesn't have all the useless stuff like big GPS screen (GPS you can't update, very silly move from Porsche back then). Also, Tiptronic really ruins the experience completely. not to talk about the sound which is nowhere as good as the air cooled 964 is.
But you know I am biased and rarely prefer a modern car to it's older sibling :bah: